Archive for July, 2010

We have to look at the sky for our source and the soil below our feet for storage, says S. VISHWANATH

We know the worth of water when the well runs dry

– Benjamin Franklin

There have been prayers to the rain god in parts of Rajasthan. Frogs are getting married and ‘havans’ are being performed. News comes that the KRS dam on the Cauvery is at an abysmal low and at the Kabini reservoirs, water levels are dropping alarmingly. The Thippagondanahalli reservoir on the Arkavathy is all but empty. The Cauvery, the single largest source of water for Bangalore city, is experiencing unprecedented low flows. These are incredibly difficult times for the citizens of Bangalore as well as the institutions concerned with supplying water.

There is however a different story emerging in a few places in Bangalore. Rainwater harvesting has recently been made mandatory, with a requirement of 20 litres of storage or recharge to be created per square metre of roof area. Preceding this mandate, several households had adopted rainwater harvesting to augment their water supply.

Typically these houses have roofs that sloped towards one direction to make it easy to collect the rainwater. It is then filtered and lead into a sump. The overflow of water from the sump, if any, is led into a recharge well made specifically for this purpose. The typical recharge well is 3 ft. in diameter and 20 ft. deep.

In some houses rainwater is led directly into a recharge well or an existing open well. Since Bangalore has been receiving good rains from a 100 square metre roof area nearly 100,000 litres of rainwater becomes available for storage or for recharging the aquifer.

Good signs

Slowly the local aquifer is filling up and the wells have begun to yield water. A small half H.P. pump can now draw the 500 litres of water required per day and supply it to the household. This water is available 24/7 and is the cheapest available in the city, costing no more than Rs. 3 per 1,000 litres.

Again and again, nature is telling us that we have to work to get water and that there is no free drink. We have to look at the sky for our source and the soil below our feet for storage. Connecting the sky and the soil is the rainwater harvesting system. The well is the source to receive the rain and when the aquifer is full to enable the stored water to be drawn.

In a country so dependent on groundwater and in a city which has more than 100,000 borewells (possibly 400,000), it is imperative to recharge the shallow aquifer and to control demand. Recharge wells and open wells are excellent structures because they can take in between 1,000 and 4,000 litres per hour, compared to a recharge of 10 litres to 30 litres per square metre per day from lakes and tanks. If we protect our wells, dig more recharge wells, use the opportunity provided by rainwater harvesting learnings and ensure that wells are not polluted then we will have gone a long way in supplementing our water requirements. The impact of urban flooding too will have been minimised.

Being waterwise is to do the little things and do them right. It is also to learn from a tradition of water use and also modern science and marry them in such a way that they bring positive benefits.

Starting from the home is a good beginning, covering the city is ideal.

Every new layout should become self-sufficient in water supply. Some useful tips by S. Vishwanath

The news this week on the waterfront for Bangalore is grim. The Arkavathi, supplying water to the Thippagondanahalli reservoir, has failed to flow for some time and consequently the reservoir is dry. Water will not be pumped from it anymore into the city. When the dam was full 135 million litres per day was pumped into the city from T.G.Halli. An additional 35 million litres per day was pumped from the Hessarghatta reservoir upstream of T.G.Halli. Hessarghatta too is dry. The city has lost 170 million litres of water per day.

Till the city seeks only to exploit rivers and not to manage catchments and keep rivers flowing, such events are likely to occur. Ecological stewardship is an alien concept for our water supply institutions. They do not have the vision or the capabilities to be able to do good catchment management.

In the meantime, the city continues to grow. What should the builders, developers and residents of such layouts do for water supply and sanitation?

10-point programme

Here is the checklist:

Ban the drilling of individual borewells in the layout. Only community borewells will be drilled and water distributed equally to all plots for construction as well as for domestic consumption.

Create a storage system and network capable of delivering 24/7 water supply at a residual pressure of 10 metres and with BIS 10500 standard water quality.

Create an efficient decentralised sewage collection and treatment system. Treat sewage to levels which it can be reused for non-potable purpose and ensure that waste-water is not wasted.

Calculate the production cost of water, collection and treatment of sewage and collect money on a volumetric tariff basis to recover full costs.

Make rainwater harvesting mandatory in every house. The household should either store or recharge every drop of water falling on the plot.

Adopt recharge structures on stormwater drains so that every drop of water from the common amenities area like roads, parks and playgrounds is collected and recharged.

Adopt a simple landscaping system which is tree based and which does not demand more water than available through treated sewage. Landscapes can demand enormous water if badly designed.

Keep a record of all water and sanitation assets in both map and written form with the association. Even failed borewells need to be maintained as informative data for suitable planning.

Educate the residents on water consumption and sewage treatment and encourage conservative use of water

Employ the best skills and technologies for they are the cheapest and most sustainable in the long run in maintaining and using the assets created for water supply and sanitation

It is possible to use the 10-point sutra and be completely sustainable for water and sanitation without depending on private tankers or the city suppliers.

Time to act: Simple tests to check the presence of harmful bacteria in water are needed

Water-borne disease is one of the primary causes of morbidity and mortality, especially among children. In simple language, diarrhoea, dysentery, cholera and typhoid are all diseases caused by bacteria in water. Simple tests to determine the safety of water from a micro-biological point of view are crucial to take preventive measures.

One of the simplest is the H2S (hydrogen sulphide) strip test which is a basic indicator test of the presence of e-coli bacteria in water. The test also has the capacity to detect enteric and harmful bacteria such as salmonella and citrobacter. The presence of e-coli, an indicator bacteria, can be seen as showing the presence of cholera and typhoid.

How it works

The H2S strip test was developed by K.S. Manja and team. It is a simple pre-sterilised coated paper in a small, sealed bottle. The sealed cap of the bottle is opened with clean hands. The sample of water to be tested is filled to an appropriately marked line on the bottle. The cap is then put back and closed. The water sample is usually observed for 24 to 48 hours when kept in room temperature of between 25 to 37 degrees C.

If the sample of water and the coated paper turns black it indicates the presence of coliform bacteria or faecal contamination of water, making further treatment of the water necessary before consumption. Even if a certain amount of chlorine is present in water it can also be instantly removed by the medium present in the bottle.

All types of drinking water — whether from pipelines, wells, borewells, rainwater, ponds, rivers springs and even bottled water — can be tested, sometimes with surprising results.

The H2S test is a basic field level indicator test. If necessary, detailed investigations can begin after the establishment of the presence of unwanted bacteria. The test is low cost and easy to conduct unlike laboratory-based tests which tend to be complex and costly. The system is rugged and has a high shelf life and therefore can be used for years if kept safely.

Multiple roles

It is easy to train people in the use of the method. Even school children can do the test and learn about water quality as part of developing general water literacy. In a recent endeavour it was used to check the quality of rooftop rainwater in the tanks constructed for the purpose of providing drinking water to school children all across Karnataka.

In another instance, drinking water stored in secondary storages/kitchen containers was checked to see the contamination that could occur when water is stored or handled in an unhygienic manner. In both cases suitable measures could be suggested to ensure that water was made potable before being consumed.

The H2S strip test is a one-time test in the sense the bottle can be used for one test only. The bottles are not easily available all over India. It may at times give a false positive result i.e. identifying the presence of harmful bacteria when perhaps there are none. It also gives a yes/no result without giving the number or amount of such bacteria in a given volume. It does not identify chemical or physical contaminants in water but only microbiological contaminants. The bottle itself is breakable, as it is made of glass. It also requires to be safely disposed of once the test is over.

Much more needs to be done to raise general awareness of this simple and easy method available and developed in India. As there are increasing reports of bacterial contamination of groundwater and pipeline water the H2S strip test can give consumers and providers a quick check on the prevention methods necessary to take control of this contamination.

Bottles should become cheaper and available in all villages and towns. In addition, people should be armed with affordable techniques to take care of the contamination either through chlorination or sterilisation of the drinking water.

Low-cost methods

No-cost or low-cost methods such as SODIS ( Solar disinfection) — which use PET bottles or glass bottles to sterilise water by keeping it in the sun for five hours or more — need to be propagated.

The H2S bottles are usually available at shops selling chemicals and allied equipment.

The local UNICEF office or the Total Sanitation Campaign office may also be of help.

In general, water wisdom lies in understanding and using simple tests to check the presence of harmful bacteria in water and taking action to avoid the harm they can cause.